| 摘要 |
<p>1345054 Character recognition systems ARTHUR KLEMT KG 10 Sept 1971 [10 Sept 1970] 42398/71 Heading G4R To reduce the effects of changes in contrast and background brightness of a character field scanned by a character recognition system at least one photo-cell is employed to view an area of the background in which no part of characters to be recognized ever appears. The signal from this cell, representing the background, is subtracted from each of the output signals of a matrix of photo-cells which view the character field. The difference signals are fed to respective resistance bridges and to an adder which forms the sum of the difference signals. The sum signal is fed to the other arm of the bridges. The signals fed to the bridges are processed in a known way to provide signals indicative of the character. If the scanned character agrees with the characteristics of a standard character one of the character-indicating signals lies within certain limits. The signals are fed to a comparator for comparison with the sum signal, the comparator output indicating the character. Instead of a single cell viewing the background several cells may be used, the average of their outputs being subtracted from the matrix outputs.</p> |
